[DISCLAIMER: The following text is taken from the U.S. War Department
publication Tactical and Technical Trends. As with all wartime
intelligence information, data may be incomplete or inaccurate. No
attempt has been made to update or correct the text. Any views or
opinions expressed do not necessarily represent those of the website.]

JAPANESE
AIR BOMBS (ARMY AND NAVY)

There is no separate Japanese air force such as the RAF and Luftwaffe and
aerial operations are carried on by special departments of the Army and
Navy. There is, therefore, a very distinct difference between the aircraft, bombs,
fuzes, etc., produced by these two departments, both of which seem to have
developed quite independently. Army aircraft are land-based entirely, whereas
Navy aircraft are both carrier-based and land-based. Bomb racks, release
mechanisms and fuze arming devices are quite different.

Listed below are the main general distinctions between army and navy
types of bombs and fuzes. It is fully realized that these distinctions do not exist
in all cases.

a. Body Construction

Army types have a screw-in nose-piece, and a tail unit welded to the main
body. In naval types the tail cone is connected to the body by a separate internal
insert; the nose is located by rivets or a weld, while the tail-unit is affixed by set
screws; it is thus possible to remove the tail piece easily, by removing the set
screws but not the nose piece. Suspension lugs are quite different because of the
different types of release mechanisms; the army type is rectangular and hinged,
while the navy type is a fixed U-bolt.

b. HE Fillings and Exploders

The general HE filling in army bombs is picric acid, contained in waxed
cardboard containers and comprising three portions - nose, body, tail. Each
portion is a loose fit inside the bomb and is retained by wax. The usual HE filling
in navy bombs is hexanite and anisol mixture, or trinitroanisol, poured into the
casing; the tail cone filling - if present - is separate and divided from the main
portion by a cardboard washer. There are small standard army type boosters
which initiate the main fillings, by means of an auxiliary picric acid booster. No
navy standard type auxiliary boosters exist, the main fillings being initiated direct
by a large standard booster screwed directly into the fuze base.

c. Markings

Markings on bombs give an indication of the arsenals in which manufactured.
Some arsenals, such as at Tokyo, Osaka, Nagoya, Sakai are military; others (e.g.
at Kure) are naval. Each arsenal has its characteristic Japanese inscription. It
is thus easily possible to find the type (i.e. service) of bomb by noting the arsenal
of manufacture. Naval munitions are usually marked with an anchor.

d. Bomb Classification
The following is a list of Japanese army and navy aircraft bombs taken
from a British official source. It may be noted that bombs dropped on one area
are normally of the same service. In the Ceylon raids (carrier-based aircraft)
naval types were dropped.